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Limiting the scope of a patent claim to an unclaimed feature of a specification embodiment— even where it is the only described embodiment— is rarely successful. This is because patent specifications almost never describe an embodiment with words that manifest a clear intention to limit the scope of their invention to particular features. Earlier this week, in Secure Web Conference Corp. v. Microsoft Corp., the Federal Circuit affirmed a district court claim construction that limited claims to an unclaimed feature of a specification embodiment. The CAFC agreed with the lower court that the described embodiment was limiting as capturing the essence of the invention.

To avoid prior art under the Broadest Reasonable Interpretation (BRI) rubric, Patentees often advocate for a narrow claim read before the USPTO Patent Trial & Appeal Board (PTAB). As such, this district court appeal decision may be of particular interest to Patentees.

In reviewing Secure Web patents 6,856,686 & 6,856,687, the lower court held that the claimed "security devices" of the '686 patent and "network communication devices" of the '687 were stand-alone devices. (i.e., external and separate from other claimed devices). The Markman Order provided a clear non-infringement position for Microsoft, hence the appeal.

Although the claims did not explicitly recite that these devices were stand-alone, the Federal Circuit agreed with the narrow read, explaining (here):

All descriptions of the security device in the intrinsic record are limited to a stand-alone device. . . . .the specification touts the separate and stand-alone nature of the security device as an advantage.

First, the Background of the Invention section characterizes the security device as an add-on component to existing microprocessor-based devices, explaining that “as many users already possess telephones, facsimile machines and computers, it is desirable to provide a security device capable of performing [security] functions in connection with these existing devices.” The remainder of the specification reinforces that using a stand-alone security device is not mere happenstance.

For example, in an embodiment where the microprocessor-based device is a computer, the specification explains that separating the security device from the microprocessor-based device advantageously allows a user to secure data residing in the microprocessor-based device in the event it is lost or stolen. . . . .“In this way, even if the computer 40 becomes lost or stolen, unauthorized access to the encrypted file could still be frustrated by adequately safeguarding device 10.” This benefit is derived directly from the separation of the security device and the computer.

Not only does the specification describe specific advantages gained from separating the security device from the microprocessor-based device, but also it never once suggests embedding the security device within the microprocessor-based device. Figure 2 provides a detailed view of the security device itself. Figure 2 shows, and the associated text describes, several sets of input/output ports on the security device so that various microprocessor-based devices may become “coupled” to it. Figure 2 and its associated text also indicate that the security device has its own microcontroller. The existence of ports for interfacing with other devices and the use of an independent microcontroller exhibit the level of self-sufficiency expected of a stand-alone device.

All descriptions of the security device in the intrinsic record are limited to a stand-alone device. . . . .the specification touts the separate and stand-alone nature of the security device as an advantage.

First, the Background of the Invention section characterizes the security device as an add-on component to existing microprocessor-based devices, explaining that “as many users already possess telephones, facsimile machines and computers, it is desirable to provide a security device capable of performing [security] functions in connection with these existing devices.” The remainder of the specification reinforces that using a stand-alone security device is not mere happenstance.

For example, in an embodiment where the microprocessor-based device is a computer, the specification explains that separating the security device from the microprocessor-based device advantageously allows a user to secure data residing in the microprocessor-based device in the event it is lost or stolen. . . . .“In this way, even if the computer 40 becomes lost or stolen, unauthorized access to the encrypted file could still be frustrated by adequately safeguarding device 10.” This benefit is derived directly from the separation of the security device and the computer.

Not only does the specification describe specific advantages gained from separating the security device from the microprocessor-based device, but also it never once suggests embedding the security device within the microprocessor-based device. Figure 2 provides a detailed view of the security device itself. Figure 2 shows, and the associated text describes, several sets of input/output ports on the security device so that various microprocessor-based devices may become “coupled” to it. Figure 2 and its associated text also indicate that the security device has its own microcontroller. The existence of ports for interfacing with other devices and the use of an independent microcontroller exhibit the level of self-sufficiency expected of a stand-alone device.

We are mindful not to limit claims to preferred embodiments, but in this case, the district court did not err in concluding that Figures 1 and 2 depict the essence of the claimed invention rather than a preferred embodiment. Particularly, the specification describes Figure 1 as depicting “a communication system according to the present invention” and Figure 2 as depicting “a telecommunications security device according to the instant invention.” While the specification later describes Figure 2 as “a block diagram of a preferred form of the security device according to the instant invention” this statement does not change the understanding of “security device” at least because the specification repeatedly notes the importance of using an external security device, reinforcing that the security device of the invention is limited to stand-alone security devices. Not only does the specification describe specific advantages gained from separating the security device from the microprocessor-based device, but also it never once suggests embedding the security device within the microprocessor-based device.

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